From 8b85d35fd79869766f678cbdc27bfaebe37b5527 Mon Sep 17 00:00:00 2001
From: John Stark <jhnstrk@users.noreply.github.com>
Date: Thu, 18 Apr 2024 19:55:54 +0100
Subject: [PATCH] Fix headers being carried between parts. fixes #63 (#135)

The contents of the headers dict wasn't cleared when a new part started, If the second part didn't overwrite the header value, it would appear in the wrong part.
---
 multipart/multipart.py                        |  4 +++-
 .../http/mixed_plain_and_base64_encoding.http | 23 +++++++++++++++++++
 .../http/mixed_plain_and_base64_encoding.yaml | 18 +++++++++++++++
 3 files changed, 44 insertions(+), 1 deletion(-)
 create mode 100644 tests/test_data/http/mixed_plain_and_base64_encoding.http
 create mode 100644 tests/test_data/http/mixed_plain_and_base64_encoding.yaml

diff --git a/multipart/multipart.py b/multipart/multipart.py
index 0505c1b..1ad5011 100644
--- a/multipart/multipart.py
+++ b/multipart/multipart.py
@@ -1613,7 +1613,9 @@ def _on_end() -> None:
             is_file = False
 
             def on_part_begin():
-                pass
+                # Reset headers in case this isn't the first part.
+                nonlocal headers
+                headers = {}
 
             def on_part_data(data: bytes, start: int, end: int) -> None:
                 nonlocal writer
diff --git a/tests/test_data/http/mixed_plain_and_base64_encoding.http b/tests/test_data/http/mixed_plain_and_base64_encoding.http
new file mode 100644
index 0000000..9de1a3b
--- /dev/null
+++ b/tests/test_data/http/mixed_plain_and_base64_encoding.http
@@ -0,0 +1,23 @@
+----boundary
+Content-Type: text/plain; charset="UTF-8"
+Content-Disposition: form-data; name=field1
+Content-Transfer-Encoding: base64
+
+VGVzdCAxMjM=
+----boundary
+Content-Type: text/plain; charset="UTF-8"
+Content-Disposition: form-data; name=field2
+
+This is a test.
+----boundary
+Content-Type: text/plain; charset="UTF-8"
+Content-Disposition: form-data; name=field3
+Content-Transfer-Encoding: base64
+
+VGVzdCBzdHJpbmcuCg==
+----boundary
+Content-Type: text/plain; charset="UTF-8"
+Content-Disposition: form-data; name=field4
+
+This is also a test.
+----boundary--
\ No newline at end of file
diff --git a/tests/test_data/http/mixed_plain_and_base64_encoding.yaml b/tests/test_data/http/mixed_plain_and_base64_encoding.yaml
new file mode 100644
index 0000000..31bfe77
--- /dev/null
+++ b/tests/test_data/http/mixed_plain_and_base64_encoding.yaml
@@ -0,0 +1,18 @@
+boundary: --boundary
+expected:
+  - name: field1
+    type: field
+    data: !!binary |
+      VGVzdCAxMjM=
+  - name: field2
+    type: field
+    data: !!binary |
+      VGhpcyBpcyBhIHRlc3Qu
+  - name: field3
+    type: field
+    data: !!binary |
+      VGVzdCBzdHJpbmcuCg==
+  - name: field4
+    type: field
+    data: !!binary |
+      VGhpcyBpcyBhbHNvIGEgdGVzdC4=